Denton R M, McCormack J G, Midgley P J, Rutter G A
Department of Biochemistry, University of Bristol Medical School, U.K.
Biochem Soc Symp. 1987;54:127-43.
Three key dehydrogenases in the mitochondria of higher animals have been found to be activated by Ca2+ ions; these are pyruvate dehydrogenase and two enzymes in the citric acid cycle, NAD-isocitrate dehydrogenase and oxoglutarate dehydrogenase. Activation can also be demonstrated within permeabilized and intact mitochondria. Evidence is summarized that when hormones and other extracellular stimuli increase the cytoplasmic concentration of Ca2+, then this results in an increase in the intramitochondrial concentration of Ca2+. In this way, rates of pyruvate oxidation and citric acid cycle flux are increased, and hence there is an increase in NADH supply for the respiratory chain under conditions where there is an enhanced demand for ATP. In contrast, the activation of pyruvate dehydrogenase which is observed in adipose and other tissues exposed to insulin is brought about by a Ca2+-independent mechanism.
已发现高等动物线粒体中的三种关键脱氢酶可被钙离子激活；它们是丙酮酸脱氢酶以及柠檬酸循环中的两种酶，即NAD -异柠檬酸脱氢酶和氧代戊二酸脱氢酶。在通透化和完整的线粒体中也能证明这种激活作用。有证据表明，当激素和其他细胞外刺激增加细胞质中钙离子浓度时，这会导致线粒体内钙离子浓度升高。通过这种方式，丙酮酸氧化速率和柠檬酸循环通量增加，因此在ATP需求增加的情况下，呼吸链的NADH供应也会增加。相比之下，在脂肪组织和其他暴露于胰岛素的组织中观察到的丙酮酸脱氢酶激活是由一种不依赖钙离子的机制引起的。
